The National Health and Nutrition Examination Survey (NHANES III) was conducted by the National Center for Health Statistics (NCHS) from 1988 to 1994. NIDR staff contributed to and coordinated an oral health component. There were four overall objectives of the oral health component of Third National Health and Nutrition Examination Survey (NHANES III), Phase I (1988-1991) and Phase II (1992-1994): (1) to estimate the magnitude and relative frequency of selected oral diseases, disorders, and conditions; (2) to describe the distribution of these oral conditions among sociodemographic groups; (3) to describe the relationship between these conditions and selected risk factors; and (4) to document and investigate reasons for secular trends in these oral diseases, disorders, and conditions. Division staff designed the oral health component examination procedures and household questions and monitored the data collection phase. Large, complex sample surveys offer many unusual challenges for analysts and computer programmers in addition to the volume of data involved. These complexities include: the need for special software, custom programming, and procedures for calculation of estimates and standard errors that take complex sampling design into account; the difficulties in ensuring that data from national surveys conducted over time are comparable; and the need for procedures to control for differences in population structure across race or ethnic groups. Branch staff create oral health status indices, develop and execute statistical analysis plans, resolve statistical and quality control issues, and help interpret the findings.